The invention relates to methods for controlling an engine braking device of an internal combustion engine of a motor vehicle during an up-shift process of a transmission device of the internal combustion engine and an internal combustion engine for a motor vehicle acting on selected cylinders for controlling a braking operation of the engine.
Such methods and internal combustion engines are already known for example known from DE 39 37 302 A1. An internal combustion engine comprises for example, several cylinders, an engine braking device, a fuel supply device and a shiftable transmission device, which itself comprises an input shaft that can be coupled to the crankshaft of the internal combustion engine by means of a clutch. The engine braking device is used for assisting the transmission device during an upshift process, wherein the upshift process is sensed by means of sensors. With a disengaged gear of the transmission device and a closed clutch, the cylinders are put into the braking operation by a simultaneous activating of the engine braking device and blocking of the fuel supply of the cylinders by means of the fuel supply device. This results in a rapid speed reduction of the internal combustion engine and the input shaft of the transmission device connected to the crankshaft via the closed clutch, so that the shifting time necessary for engaging a higher gear is reduced and a shortening of the traction force interruption is achieved in the power train. After reaching a target difference in speed between gearwheels of the transmission device to be shifted, the up-shift process can be carried out in a speed-synchronized manner and the fuel supply of the cylinders can again be increased after the deactivation of the engine braking device for the build-up of the torque. It is also conceivable that the transmission device has a transmission brake or a blocking synchronization. The transmission brake or the blocking synchronization synchronizes the speeds of the gearwheels to be shifted during an up-shift when the clutch is opened, so that the speed of the crankshaft of the internal combustion engine is adapted to a speed of the input shaft of the transmission device in this case.
The fact that the switch-on or switch-off down times which are necessary for activating or deactivating the engine braking device of the known method and of the known internal combustion engines are comparatively large and lead to an undesired prolongation of the up-shift process is disadvantageous. This is undesired amongst other things due to a low operating comfort.
It is the object of the present invention to provide a method and an internal combustion engine of the type mentioned at the outset, which enable a shortening of the up-shift process and an increase of the operating comfort.